Materials that produce color change upon stimulation with energy such as light or heat may have possible applications in imaging. For example, such materials may be found in thermal printing papers and instant imaging films. Generally, the materials and compositions known so far may require a multifilm structure and further processing to produce an image (e.g., instant imaging films such as Polaroid). And in the case of facsimile and thermal head media, high energy input of greater than 1 J/cm2 is needed to achieve good images. The compositions in multifilm media may require control of diffusion of color-forming chemistry and further processing, and are in separate phases and layers. Most thermal and facsimile paper coatings consist of coatings prepared by preparing fine dispersions of more than two components. The components mix and react upon application of energy, resulting in a colored material. To the necessary mixing, the particles need to contact across three or more phases or layers and merge into a new phase. Because of these multiple phases and layers, high energy is required to perform this process. For example, a relatively powerful carbon dioxide laser with an energy density of 3 J/cm2 at times of much greater than 100 μs may be needed to produce a mark. In some instances, this high energy application may cause damage to the imaging substrate. In many situations, it may be desirable to produce a visible mark more efficiently using either a less intense, less powerful, and/or shorter energy application. Therefore, there is a need for fast marking coatings, possibly composed of fewer than three phases and in single layer. Single layer color-forming materials, initiated and addressable by radiation, particularly with energy density of less than 1 J/cm2 delivered in less than 100 μs is hereto unknown.